Study Questions Short Follow-Up Intervals For ‘Probably Benign’ Mammographic Findings

 Behind the Cancer Headlines®

March 19, 2003 


Among women whose mammograms yield a "probably benign" finding and are subsequently recommended for short-interval follow-up, the frequency of breast cancers diagnosed within two years of the screening is roughly 1%, according to a study published in the Journal of the National Cancer Institute. This relatively low probability of breast cancer suggests that the 3- to 6-month follow-up interval currently recommended for this group should be reconsidered, the study authors conclude.  

Mammographic findings are grouped into one of five categories based on their probability of being cancerous. These categories range from category 1 ("negative") to category 5 ("highly suggestive of malignancy"), and lead to specific recommendations for follow-up. Women who receive a category 3 ("probably benign") finding are typically recommended to undergo follow-up testing every 3 to 6 months. However, there is limited evidence to support this recommendation, and researchers are beginning to question whether such short-interval follow-up is necessary.  

Shagufta Yasmeen, M.D., of the University of California, Davis, and colleagues examined the incidence of breast cancer among 58,408 postmenopausal women who were screened for breast cancer at 40 participating centers as part of the Women's Health Initiative.  

Five percent, or 2,927 of these women had received recommendations for short-interval follow-up after their baseline mammogram. Across the participating centers, the range of short interval follow-up recommendations was from 1.2% to 9.8%. After two years of follow-up, the incidence of newly diagnosed breast cancer among this group was 1.0%, compared with breast cancer incidence rates of 0.6% and 0.5% for women whose baseline mammograms were described as "benign" and "negative," respectively.  

These findings suggest that a mammographic recommendation for short-interval follow-up was associated with a low positive predictive value for breast cancer among postmenopausal women during a 2-year follow-up.  

"Given the fact that recommendation for short-interval follow-up may account for over 40% to 50% of abnormal screening mammograms, our results should stimulate re-examination of the criteria used to make this recommendation," the authors conclude. They add that their results and those of other recent studies suggest that a 1-year follow-up of probably benign findings may be as or more appropriate than a 6-month follow-up.  

In an accompanying editorial, Karla Kerlikowske, M.D., of the San Francisco Veterans Affairs Medical Center and the University of California at San Francisco, and her colleagues point out that short-interval follow-up is reasonable if the prevalence of probably benign lesions is low. However, if the prevalence of probably benign lesions recommended for short-interval follow-up is high, as suggested by this study, a large number of women may be undergoing unnecessary follow-up of benign tumors, they say. 

"Further research is required to know whether probably benign lesions can be safely characterized and followed directly from a screening examination and whether this approach maximizes the identification of early-stage breast cancers while limiting the number of women undergoing surveillance and biopsy," the editorialists conclude.  



Journal of the National Cancer Institute, March 19, 2003